Soft polypropylene with improved optical properties

Abstract

Polymer composition comprising a propylene copolymer and a styrenic based elastomer.

The invention claimed is: 
     
       1. Polymer composition comprising:
 (a) a propylene copolymer (A) having:
 (a1) a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 in the range of more than 2.0 to 15.0 g/10 min, 
 (a2) a comonomer content in the range of more than 7.5 to 16.5 wt. %, and 
 (a3) a xylene cold soluble content (XCS) determined according to ISO 16152 (25° C.) in the range of 25.0 to 55.0 wt. %, wherein, 
 (a4) the comonomer content of xylene cold soluble (XCS) fraction of the propylene copolymer (A) is in the range of 14.0 to 30.0 wt. %, and 
 (a5) an intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction of the propylene copolymer (A) is in the range of equal or more than 1.5 to equal or below 3.0 dl/g, wherein the intrinsic viscosity (IV) is determined according to DIN ISO 1628/1 (in Decalin at 135° C.), and 
 
 (b) styrenic based elastomer(s) (B) having a styrene content in the range of 5 to equal or below 15 wt. %, 
 wherein further the weight ratio of propylene copolymer (A) and the styrenic based elastomer(s) (B) [(A)/(B)] is in the range of 9/1 to 3/2. 
 
     
     
       2. Polymer composition according to  claim 1 , wherein the propylene copolymer (A):
 (a) has a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 in the range of more than 2.5 to below 5.0 g/10 min, and/or 
 (b) fulfills inequation (I): 
 
       
         
           
             
               0.3 
               ≤ 
               
                 
                   Co 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     total 
                     ) 
                   
                 
                 
                   Co 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     XCS 
                     ) 
                   
                 
               
               ≤ 
               0.7 
             
           
         
         wherein, Co (total) is the comonomer content [wt. %] of the propylene copolymer (A), 
         Co (XCS) is the comonomer content [wt. %] of the xylene cold soluble fraction (XCS) of the propylene copolymer (A), and/or 
         (c) fulfills inequation (II): 
       
       
         
           
             
               
                 
                   Co 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     total 
                     ) 
                   
                 
                 XCS 
               
               ≤ 
               0.30 
             
           
         
         wherein, Co (total) is the comonomer content [wt. %] of the propylene copolymer (A), 
         XCS is the content of the xylene cold soluble fraction (XCS) [wt. %] of the propylene copolymer (A). 
       
     
     
       3. Polymer composition according to  claim 1 , wherein the xylene cold insoluble (XCI) fraction of the propylene copolymer (A) has a comonomer content in the range of 1.5 to 6.0 wt. %. 
     
     
       4. Polymer composition according to  claim 1 , wherein the propylene copolymer (A) is a heterophasic propylene copolymer (RAHECO) comprising a matrix (M) and an elastomeric propylene copolymer (E) dispersed in said matrix (M), wherein said matrix (M) is a random propylene copolymer (R-PP). 
     
     
       5. Polymer composition according to  claim 4 , wherein:
 (a) the weight ratio between the matrix (M) and the elastomeric propylene copolymer (E) is 50/50 to 90/10, and/or 
 (b) the comonomer content of the random propylene copolymer (R-PP) is in the range of 3.0 to 12.0 wt. %, and/or 
 (c) the random propylene copolymer (R-PP) has a xylene cold soluble (XCS) fraction in the range of 5.0 to 50.0 wt. %. 
 
     
     
       6. Polymer composition according to  claim 4 , wherein the elastomeric propylene copolymer (E) has a comonomer content in the range of 14.0 to 35.0 wt. %. 
     
     
       7. Polymer composition according to  claim 1 , wherein the styrenic based elastomer(s) (B) is(are) (a) styrene-ethylene/butylene-styrene (SEBS) block copolymer(s) (B-1) and/or (a) hydrogenated styrene-vinyl isoprene (SIS) block rubber(s) (B-2). 
     
     
       8. Polymer composition according to  claim 1 , wherein the polymer composition comprises as styrenic based elastomer(s) (B) only (a) styrene-ethylene/butylene-styrene (SEBS) block copolymer(s) (B-1) and/or (a) hydrogenated styrene-vinyl isoprene (SIS) block rubber(s) (B-2). 
     
     
       9. Polymer composition according to  claim 1 , wherein the styrenic based elastomer (B) has a melt flow rate MFR 2  (230° C.) of below 10.0 g/10 min. 
     
     
       10. Polymer composition according to  claim 1 , wherein the styrenic based elastomer(s) (B) has a density of below 0.905 g/m 3 . 
     
     
       11. A film, comprising the polymer composition as defined in  claim 1 . 
     
     
       12. A container, comprising a film, the film including a polymer composition, the polymer composition comprising:
 (a) a propylene copolymer (A) having:
 (a1) a melt flow rate MFR2 (230° C.) measured according to ISO 1133 in the range of more than 2.0 to 15.0 g/10 min, 
 (a2) a comonomer content in the range of more than 7.5 to 16.5 wt. %, and 
 (a3) a xylene cold soluble content (XCS) determined according to ISO 16152 (25° C.) in the range of 25.0 to 55.0 wt. %, wherein, 
 (a4) the comonomer content of xylene cold soluble (XCS) fraction of the propylene copolymer (A) is in the range of 14.0 to 30.0 wt. %, and 
 (a5) an intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction of the propylene copolymer (A) is in the range of equal or more than 1.5 to equal or below 3.0 dl/g, wherein the intrinsic viscosity (IV) is determined according to DIN ISO 1628/1 (in Decalin at 135° C.), and 
 
 (b) styrenic based elastomer(s) (B) having a styrene content in the range of 5 to equal or below 15 wt. %, 
 wherein further the weight ratio of propylene copolymer (A) and the styrenic based elastomer(s) (B) [(A)/(B)] is in the range of 9/1 to 3/2. 
 
     
     
       13. The container according to  claim 12 , wherein the container or the film has been subjected to a sterilisation treatment.